Planers and jointers are used to smooth or plane non-planar surfaces on workpieces such as wooden planks or boards. These planers and jointers include rotary cutting head assemblies having blades with straight elongate cutting edges. The cutting edges rotate about a longitudinal axis and shave material from the surface of the workpiece which is to be planed. If the cutting edges on the blades are perfectly straight, the cutting edges sweep out a cylindrical surface as the cutting head assemblies rotate. When the cutting edges engage an uneven or non-planar work surface on a workpiece, portions of the work surface are planed or shaved away. This planing operation is continued until the entire work surface is planar.
When a workpiece contains an unusually hard anomaly, such as nail or a knot, the cutting edges on the blades can become nicked or damaged. As the cutting head assembly rotates at high speeds, usually all of the cutting edges on the blades are nicked or damaged in a plane perpendicular to the longitudinal axis of the cutting head assembly in which the anomaly lies. Accordingly, the cutting edges will no longer sweep out a perfect cylindrical surface, but rather, will generate a generally cylindrical surface having annular grooves therein where the cutting edges are nicked. Correspondingly, a complementary ridge will be formed on the work surface being cut by the blades. Therefore, the work surface which is planed will no longer be planar.
The nicked blades will have to be replaced or reworked to provide straight cutting edges in order to properly plane work surfaces. As a result, producing ideally planar surfaces on workpieces can be expensive. Also, considerable time must be taken to disassemble the cutting head assembly, replace the blades, and reassemble the cutting head assembly.
The present invention is intended to overcome these shortcoming of planers and jointers using conventional cutting head assemblies.